Primary Carbide Refinement In Hypereutectic High Chromium Cast Irons

Abstract

The invention relates to a process for manufacturing a casting of a hypereutectic high chromium cast iron (“HCCI”) including: forming a melt of a molten hypereutectic high chromium cast iron and a carbide modifier, and forming a solid casting of the hypereutectic high chromium cast iron. The invention further relates to a carbide-modified hypereutectic high chromium cast iron (“HCCI”) that includes a dispersion of a primary carbide phase in a ferrous matrix, with the primary carbide phase including a carbide modifier phase within the primary carbide phase that acted as a nucleation agent for the primary carbide phase.

1 . A process for manufacturing a casting of a hypereutectic high chromium cast iron (“HCCI”) including:
 forming a melt of a molten hypereutectic high chromium cast iron and a carbide modifier, and 
 forming a solid casting of the HCCI, wherein the carbide modifier is selected from borides of Ti, Zr, Hf, V, Nb and Ta, and wherein the melt comprises about 0.01 wt. % to 2 wt. % carbide modifier. 
 
     
     
         2 . The process defined in  claim 1  including forming the molten hypereutectic high chromium cast iron without the carbide modifier and adding the carbide modifier to the molten hypereutectic high chromium cast iron to form the melt. 
     
     
         3 . The process defined in  claim 2  wherein the carbide modifier is added to the molten hypereutectic high chromium cast iron in a solid form. 
     
     
         4 . The process defined in  claim 3  wherein the carbide modifier is added to the molten hypereutectic high chromium cast iron in the form of a powder. 
     
     
         5 . The process defined in  claim 3  wherein the carbide modifier is added to the molten hypereutectic high chromium cast iron in the form of a pellet. 
     
     
         6 . The process defined in  claim 2  wherein the carbide modifier is added to the molten hypereutectic high chromium cast iron in a master alloy. 
     
     
         7 - 36 . (canceled) 
     
     
         37 . The process defined in  claim 1  wherein forming a solid casting of the hypereutectic high chromium cast iron includes controlling solidification of the molten hypereutectic high chromium cast iron to form equiaxed-shaped primary carbides. 
     
     
         38 . The process defined in  claim 1  wherein the carbide modifier is titanium boride and wherein the melt comprises about 0.01 wt. % to 0.8 wt. % carbide modifier. 
     
     
         39 . A carbide-modified hypereutectic high chromium cast iron (“HCCI”) casting manufactured according to the process defined in  claim 1 , wherein the hypereutectic HCCI includes a dispersion of primary carbides in a ferrous matrix, wherein the primary carbides are at least 5% by volume smaller than primary carbides produced under the same processing conditions without the carbide modifier in the hypereutectic high chromium cast iron. 
     
     
         40 . The carbide-modified hypereutectic high chromium cast iron defined in claim  9  wherein the hypereutectic high chromium cast iron has a lower percentage of needle-shaped primary carbides and a higher percentage of equiaxed-shaped primary carbides by volume than primary carbides produced under the same processing conditions without the carbide modifier in the hypereutectic high chromium cast iron. 
     
     
         41 . The carbide-modified hypereutectic high chromium cast iron defined in claim  9  wherein the carbide modifier is added to comprise 0.01 wt. % to 2 wt. % of the HCCI during casting, and the carbide modifier phase is a boride of Ti, Zr, Hf, V, Nb, or Ta. 
     
     
         42 . The carbide-modified hypereutectic high chromium cast iron defined in claim  9  wherein the carbide modifier is added to comprise 0.01 wt. % to 0.8 wt. % of the HCCI during casting, and the carbide modifier phase is titanium boride. 
     
     
         43 . A component for use in mining and mineral processing applications manufactured from a hypereutectic high chromium cast iron defined in claim  9 .